datus and s. torvicornis, is absent in the new taxon;
(4) although the morphology of the teeth of s. mattoxi
and s. ovamboensis are similar, the apex of the finger
presents a ventral subapical lobe in the former, while
it is smooth and acuminate in the latter. In comparison to the species of the mackini subgroup, S. mattoxi
presents the following differences: (1) a small proximal tooth on the finger, (2) crenate dorsal margin of the
thumb, which is a unique feature within all New World
species (S. antillensis and S. moorei present, however,
a dorsal thumb margin with a series of spiniform structures), and (3) females with uniramous ovaries.
Distribution. Streptocephalus mattoxi is endemic to
Kenedy County, Texas, USA.
Etymology. The species is named in memory of Dr
Norman T. Mattox (1910-1960), in recognition of his
contributions to our knowledge of the North American
phyllopods (Garth, 1960).
mackini subgroup
Streptocephalus antillensis Mattox, 1950
(Fig. 7 A-F)
Streptocephalus antillensis Mattox, 1950; Dexter,
1959; Moore, 1966; Brtek, 1974; Belk, 1975; Spicer,
1985.
Type material. Holotype USNM 91085, paratypes
USNM 91086, LACM 50-97.1.
Type locality. Mona Island, Puerto Rico.
Material examined. Paratypes LACM 50-97.1,
1 d' 10.0 mm, 5 Q Q 8.5 (8.3-9.0) mm; USNM
91086 paratypes 3 d' d' 10.3 (9.0-11.4) mm (1 d'
used for SEM), 3 Q Q 8.2 (7.9-8.7) mm.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus; dorsolateral side of base of
thumb with a small protuberance; apex of spur with
a swollen part which ends in a subacuminate prolongation; lateral lamella with an acute angle between
thumb and spur; inner lamella medially produced but
not forming a deep cavity; distal part of thumb dorsally curved along its extension, apex acuminate; dorsal
margin of distal part of thumb with a series of about
18 spiniform structures; finger bigeniculate, two digitiform teeth anteriorly oblique on inner dorsal side of
proximal part; proximal one smaller than distal one;
27
apex of finger with a SUbapical swollen part, ending in a lamelliform structure, slightly bilobed at tip;
frontal appendage simple, short, bilobed at tip; genitalia without linguiform outgrowths; cercopods setose
along inner and lateral borders; anus terminal.
Female. Ovaries biramous, variably extending
from thoracic segments 6-7 to abdominal segments 12; sphaerical cystc ornamented by ribs forming reduced
polygonal cells.
Differential diagnosis. Within the mackini subgroup,
S. antillensis and S. moo rei present the most similarities. Only these species of the subgroup have a series
of spiniform structures on the dorsal margin of the distal part of the thumb. The main differences between
them are: (1) S. moorei has a long curved process
on the dorsal side of the base of the thumb (Fig. 11
A-C, F), while S. antillensis presents two digitform
teeth (Fig. 11 B), and (3) the apex of the finger in S.
moo rei is acuminate and bears a SUbapical digitiform
structure, ventrolaterally directed (Fig. 11 C), while
in S. antillensis the apex has a subapical swollen part,
but finishes in a lamelliform structure (Fig. 7 C, F).
Comparing S. antillensis with the African species of
the torvicornis subgroup, i.e. S. ovamboensis, S. rubricaudatus, and S. torvicornis, which all have a spinose
thumb, strong differences are found: (1) S. antillensis
has a finger with a subapically swollen apex, finishing
lamellar, while the African forms have a finger with
a long and acuminate apex; (2) the denticle between
the distal part of the thumb and the spur shown by the
African species, is absent in S. antillensis; (3) S. rubricaudatus and S. torvicornis have a small tooth at the
base of the distal tooth, which is absent in S. antillensis;
(4) the pair of linguiform genital outgrowths present in
the three African forms, is absent in S. antillensis, and
(5) the biramous ovaries of S. antillensis females.
Distribution. S. antillensis is known only from the type
locality.
Streptocephalus dorothae Mackin, 1942
(Fig. 8 A-F)
Streptocephalus dorothae Mackin, 1942; Dexter,
1959; Moore, 1966; Brtek, 1974; Belk, 1975; Pennak, 1989; Spicer, 1985.
Type material. Syntypes USNM 79019.
Type locality. 20 mi S Santa Fe, Santa Fe County, New
Mexico, USA.
(4) although the morphology of the teeth of s. mattoxi
and s. ovamboensis are similar, the apex of the finger
presents a ventral subapical lobe in the former, while
it is smooth and acuminate in the latter. In comparison to the species of the mackini subgroup, S. mattoxi
presents the following differences: (1) a small proximal tooth on the finger, (2) crenate dorsal margin of the
thumb, which is a unique feature within all New World
species (S. antillensis and S. moorei present, however,
a dorsal thumb margin with a series of spiniform structures), and (3) females with uniramous ovaries.
Distribution. Streptocephalus mattoxi is endemic to
Kenedy County, Texas, USA.
Etymology. The species is named in memory of Dr
Norman T. Mattox (1910-1960), in recognition of his
contributions to our knowledge of the North American
phyllopods (Garth, 1960).
mackini subgroup
Streptocephalus antillensis Mattox, 1950
(Fig. 7 A-F)
Streptocephalus antillensis Mattox, 1950; Dexter,
1959; Moore, 1966; Brtek, 1974; Belk, 1975; Spicer,
1985.
Type material. Holotype USNM 91085, paratypes
USNM 91086, LACM 50-97.1.
Type locality. Mona Island, Puerto Rico.
Material examined. Paratypes LACM 50-97.1,
1 d' 10.0 mm, 5 Q Q 8.5 (8.3-9.0) mm; USNM
91086 paratypes 3 d' d' 10.3 (9.0-11.4) mm (1 d'
used for SEM), 3 Q Q 8.2 (7.9-8.7) mm.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus; dorsolateral side of base of
thumb with a small protuberance; apex of spur with
a swollen part which ends in a subacuminate prolongation; lateral lamella with an acute angle between
thumb and spur; inner lamella medially produced but
not forming a deep cavity; distal part of thumb dorsally curved along its extension, apex acuminate; dorsal
margin of distal part of thumb with a series of about
18 spiniform structures; finger bigeniculate, two digitiform teeth anteriorly oblique on inner dorsal side of
proximal part; proximal one smaller than distal one;
27
apex of finger with a SUbapical swollen part, ending in a lamelliform structure, slightly bilobed at tip;
frontal appendage simple, short, bilobed at tip; genitalia without linguiform outgrowths; cercopods setose
along inner and lateral borders; anus terminal.
Female. Ovaries biramous, variably extending
from thoracic segments 6-7 to abdominal segments 12; sphaerical cystc ornamented by ribs forming reduced
polygonal cells.
Differential diagnosis. Within the mackini subgroup,
S. antillensis and S. moo rei present the most similarities. Only these species of the subgroup have a series
of spiniform structures on the dorsal margin of the distal part of the thumb. The main differences between
them are: (1) S. moorei has a long curved process
on the dorsal side of the base of the thumb (Fig. 11
A-C, F), while S. antillensis presents two digitform
teeth (Fig. 11 B), and (3) the apex of the finger in S.
moo rei is acuminate and bears a SUbapical digitiform
structure, ventrolaterally directed (Fig. 11 C), while
in S. antillensis the apex has a subapical swollen part,
but finishes in a lamelliform structure (Fig. 7 C, F).
Comparing S. antillensis with the African species of
the torvicornis subgroup, i.e. S. ovamboensis, S. rubricaudatus, and S. torvicornis, which all have a spinose
thumb, strong differences are found: (1) S. antillensis
has a finger with a subapically swollen apex, finishing
lamellar, while the African forms have a finger with
a long and acuminate apex; (2) the denticle between
the distal part of the thumb and the spur shown by the
African species, is absent in S. antillensis; (3) S. rubricaudatus and S. torvicornis have a small tooth at the
base of the distal tooth, which is absent in S. antillensis;
(4) the pair of linguiform genital outgrowths present in
the three African forms, is absent in S. antillensis, and
(5) the biramous ovaries of S. antillensis females.
Distribution. S. antillensis is known only from the type
locality.
Streptocephalus dorothae Mackin, 1942
(Fig. 8 A-F)
Streptocephalus dorothae Mackin, 1942; Dexter,
1959; Moore, 1966; Brtek, 1974; Belk, 1975; Pennak, 1989; Spicer, 1985.
Type material. Syntypes USNM 79019.
Type locality. 20 mi S Santa Fe, Santa Fe County, New
Mexico, USA.